Aphids: A Model for Polyphenism and Epigenetics

Environmental conditions can alter the form, function, and behavior of organisms over short and long timescales, and even over generations. Aphid females respond to specific environmental cues by transmitting signals that have the effect of altering the development of their offspring. These epigenetic phenomena have positioned aphids as a model for the study of phenotypic plasticity. The molecular basis for this epigenetic inheritance in aphids and how this type of inheritance system could have evolved are still unanswered questions. With the availability of the pea aphid genome sequence, new genomics technologies, and ongoing genomics projects in aphids, these questions can now be addressed. Here, we review epigenetic phenomena in aphids and recent progress toward elucidating the molecular basis of epigenetics in aphids. The discovery of a functional DNA methylation system, functional small RNA system, and expanded set of chromatin modifying genes provides a platform for analyzing these pathways in the context of aphid plasticity. With these tools and further research, aphids are an emerging model system for studying the molecular epigenetics of polyphenisms

cis-Bis(2,2′-bipyridine-κ2 N,N′)dichloridocobalt(II) trihydrate

In the title complex, [CoCl2(C10H8N2)2]·3H2O, the Co(II) ion is situated on a twofold rotation axis and exhibits a slightly distorted octa­hedral geometry and is chelated by four N atoms of the two bidentate 2,2′-bipyridine ligands and two Cl− ions. The crystal packing is stabilized by hydrogen bonding formed between chloride ions and adjacent water mol­ecules. One of the two independent water molecules in the asymmetric unit is disordered over two sets of sites, each on a twofold rotation axis, in a 0.734 (17):0.269 (17) ratio

cis-Aqua­chloridobis(1,10-phenanthroline-κ2 N,N′)cobalt(II) chloride 2.5-hydrate

In the title complex, [CoCl(C12H8N2)2(H2O)]Cl·2.5H2O, the CoII ion is coordinated by four N atoms of two bis-chelating 1,10-phenanthroline (phen) ligands, one water mol­ecule and a chloride ligand in a distorted octa­hedral environment. The dihedral angle between the two phen ligands is 84.21 (3)°. In the crystal structure, complex mol­ecules and chloride ions are linked into centrosymmetric four-component clusters by inter­molecular O—H⋯Cl hydrogen bonds. Of the 2.5 solvent water mol­ecules in the asymmetric unit, two were refined as disordered over two sites with fixed occupancies of ratios 0.50:0.50 and 0.60:0.40, while another was refined with half occupancy

Dichlorido(dimethyl­glyoximato-κ2 N,N′)(dimethyl­glyoxime-κ2 N,N′)cobalt(III)

In the title compound, [Co(C4H7N2O2)Cl2(C4H8N2O2)], the CoIII ion has a distorted octa­hedral coordination environment. The equatorial plane consists of four N atoms, two each from the dimethyl­glyoxime and dimethyl­glyoximate ligands, while the two axial positions are occupied by two chloride ions. Strong intra­molecular O—H⋯O hydrogen bonds are observed between the dimethyl­glyoxime and dimethyl­glyoximate ligands. Mol­ecules are linked into a chain running along the [101] direction by O—H⋯O and C—H⋯Cl hydrogen bonds. The chains are cross-linked through inter­molecular C—H⋯Cl hydrogen bonds

Two-dimensional horn imaging arrays (abstract)

A two-dimensional horn imaging array has been demonstrated at 242 and 93 GHz. In this configuration, a dipole is suspended in a pyramidal horn, fabricated by an anisotropic chemical etch technique, on a 1-µm silicon-oxynitride membrane. This approach leaves room for low-frequency lines and processing electronics. Pattern measurements on a 1.45-λ imaging array agree well with theory, show no sidelobes, and a 3-dB beamwidth of 35° and 46° for the E and H planes, respectively. Application areas include a superconducting tunnel-junction receiver for radio astronomy and imaging arrays for real-time electron density mapping in fusion plasmas. Support for this project was provided by DOE contract DE-FG03-86-ER-53225 (subcontracted from U.C.L.A.)

Monolithic millimeter-wave two-dimensional horn imaging arrays

A monolithic two-dimensional horn imaging array has been fabricated for millimeter wavelengths. In this configuration, a dipole is suspended in an etched pyramidal cavity on a 1-μm silicon-oxynitride membrane. This approach leaves room for low-frequency connections and processing electronics. The theoretical pattern is calculated by approximating the horn structure by a cascade of rectangular-waveguide sections. The boundary conditions are matched at each of the waveguide sections and at the aperture of the horn. Patterns at 93 and 242 GHz agree well with theory. Horn aperture efficiencies of 44±4%, including mismatch and resistive losses, have been measured. A detailed breakdown of the losses is presented. The coupling efficiency to various f-number imaging systems is investigated, and a coupling efficiency of 24% for an f0.7 imaging system (including spillover, taper, mismatch and resistive losses) has been measured. Possible application areas include imaging arrays for remote sensing, plasma diagnostics, radiometry and superconducting tunnel-junction receivers for radio astronomy

Chloridobis[diphenyl­glyoximato(1–)-κ2 N,N′](1H-imidazole-κN 3)cobalt(III) hemihydrate

The Co centre in the title compound, [Co(C14H11N2O2)2Cl(C3H4N2)]·0.5H2O, shows a slightly distorted octa­hedral coordination geometry. The glyoximate units of the mol­ecule are linked by O—H⋯O hydrogen bonds with the H atom almost in the middle of the two O atoms. The crystal packing is stabilized through inter­molecular N—H⋯O, N—H⋯N and O—H⋯Cl hydrogen bonds. The uncoordinated water mol­ecule shows half-occupation

N-Butyl­pyridine-4-thio­carboxamide

In the title mol­ecule, C10H14N2S, the n-butyl chain assumes a trans zigzag conformation. The dihedral angle between the pyridine ring and the thio­amide plane is 23.38 (8)°. The mol­ecules in the crystal structure are linked by an inter­molecular N—H⋯N hydrogen bond

(N 4-n-Butyl­pyridine-4-carbothio­amide-κN 4)chloridobis(dimethyl­glyoximato-κ2 N,N′)cobalt(III) hemihydrate

The title compound, trans-[Co(C4H7N2O2)2Cl(C10H14N2S)]·0.5H2O, contains two independent mol­ecules in the asymmetric unit in which the CoIII ions are coordinated in slightly distorted octa­hedral coordination environments. The bis-chelating glyoximate ligands, which occupy equatorial sites, are linked by interligand O—H⋯O hydrogen bonds. The dihedral angles between the mean planes of the glyoximate ligands in each mol­ecule are 2.07 (8) and 1.60 (1)°. The asymmetric unit contains a solvent water mol­ecule which is disordered over two sites with refined occupancies 0.64 (2) and 0.36 (2)

The isoquinoline PRL-295 increases the thermostability of Keap1 and disrupts its interaction with Nrf2

Transcription factor Nrf2 and its negative regulator Keap1 orchestrate a cytoprotective response against oxidative, metabolic, and inflammatory stress. Keap1 is a drug target, with several small molecules in drug development. Here, we show that the isoquinoline PRL-295 increased Keap1 thermostability in lysates from cells expressing fluorescently tagged Keap1. The thermostability of endogenous Keap1 also increased in intact cells and murine liver following PRL-295 treatment. Fluorescence Lifetime Imaging–Förster Resonance Energy Transfer (FLIM-FRET) experiments in cells co-expressing sfGFP-Nrf2 and Keap1-mCherry further showed that PRL-295 prolonged the donor fluorescence lifetime, indicating disruption of the Keap1-Nrf2 protein complex. Orally administered PRL-295 to mice activated the Nrf2transcriptional target NAD(P)H:quinone oxidoreductase 1 (NQO1) in liver and decreased the levels of plasma alanine aminotransferase and aspartate aminotransferase upon acetaminophen-induced hepatic injury. Thus, PRL-295 engages the Keap1 protein target in cells and in vivo, disrupting its interaction with Nrf2, leading to activation of Nrf2-dependent transcription and hepatocellular protection